Cylindrical head hexagon socket head screws, also referred to as hexagon socket head bolts, cup head screws, and hexagon socket head screws, have different names, but they mean the same thing. Commonly used hexagon socket head screws include grade 4.8, grade 8.8, grade 10.9, and grade 12.9. Also called hexagon socket screws, also called hexagon socket bolts. The head is either a hexagonal head or a cylindrical head.